Abstract : The Mach velocity, shock tube attenuation and the maximum test time have been measured in two narrow shock tubes of 1 inch and 1/2 inch diameter. The apparatus is described. The results are compared with theories of Mirels, Roshko and Russel. The results are also compared with experimental results on large cross-sectional shock tubes. It is shown that for pressures of 5 Torr or less the narrow shock tube attenuation and maximum test time fits within a geometric scaling factor those of large cross-sectional tubes. At pressures of 10 Torr and higher partial turbulent flow can explain the experimental results. (Author)